Combine harvester? (10,4)

I believe the answer is:

collective farm

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'combine harvester?' is the definition.
The definition and answer can be both groups as well as being singular nouns.
Perhaps they are linked in a way I don't understand?

This is the entire clue.

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(Another definition for collective farm that I've seen is " State agricultural operation".)

I've seen this clue in The Sunday Times.

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